Reverse osmosis system

ABSTRACT

A reverse osmosis system includes a sediment filter which cleans feed water from a source and from which that feed water is fed to a reverse osmosis membrane filter. Permeate from the latter is fed to a bladder within a storage tank. Concentrate from the membrane filter is fed to and used within the storage tank as squeeze water for the bladder. When a faucet that delivers permeate to the user is open, squeeze water is used to cause permeate to flow out of the storage tank through an impurity filter to supply the faucet. A valve unit is included to control the amount of squeeze water fed to the storage tank and to regulate permeate flow so that the water outletted from the faucet remains at a constant pressure and provides relief as against overpressure in the system. A proportioning valve within the valve unit serves to maintain at all times a constant ratio of concentrate to permeate flow through the membrane filter for adequate cleansing of the membrane. Also included are input-side and output-side flow monitors which provide signals to a processor that serves to indicate the status of filter conditions. There also is an advantageous faucet assembly for controlling the delivery of permeate to the user with flexibility and convenience.

RELATED APPLICATION

The present application is a division of co-pending divisionalapplication Ser. No. 07/685,680 filed Apr. 16, 1991, pending which wasin turn a division of then co-pending parent application 07/466,077filed Jan. 16, 1990 now U.S. Pat. No. 5,096,574 and all assigned to thesame assignee.

The present invention relates to reverse osmosis systems. Moreparticularly, the invention pertains to improvements in and for suchsystems by including a filter monitor, a controlling valving system, anelectronic processor and a faucet assembly.

Two major additions to water systems, particularly for residential andother smaller water consumption applications, have been an activatedcarbon bed to remove organic materials and sediment filters to removeundissolved solids. A third category which has gained interest usesreverse osmosis through a thin membrane which filters the dissolvedsolids from the water. Those solids which have been removed are washedfrom the membrane and passed to a drain. This latter filtering processis comparatively very slow, typically generating between five and twentygallons per day. Accordingly, it becomes necessary to incorporate astorage device for consumer convenience and utility. Reverse osmosissystems typically also include carbon-bed and sediment filters to bestremove all of sediment, organic materials and inorganic materials.

One or more of three different problems usually arise with presentlyavailable reverse osmosis units. They involve faucet delivery rate,permeate generation and water conservation. Many devices commonly usedincorporate an elastomeric bladder disposed within a storage tank thatseparates the filtered water from air which has been pressurized toabout five pounds per square inch. That compressed air causes deliveryof the treated water to a faucet for consumptive use. However, as thestorage tank fills with water the air is compressed and this in turnincreases the tank pressure. Accordingly, when the consumer dispensesthe water after starting with a full tank, the flow rate of thedispensed water is higher than when delivering water at a time when thestorage tank is nearly empty. In addition, that increased pressure onthe tank usually places a back pressure on the reverse osmosis membrane,resulting in decreased performance of the membrane. Finally, once thestorage tank is full the system may continue to operate in which casewater is unnecessarily wasted to the drain.

Efforts have been made to solve two of the problems mentioned above bymeans of the incorporation of a hydraulically operated valve thatcontrols operation of the system. While that approach has provenfeasible, existing configurations operate only over a very limitedpressure range. Of background interest in the art with respect toreverse osmosis systems are U.S. Pat. Nos. 4,077,883-Bray,3,746,640-Bray, 3,831,757-Gosset et al, 3,887,463-Bray, 4,176,063-Tylerand 4,391,712-Tyler et al.

It is one object of the present invention to provide a new and improvedhydraulically-operated valve which provides a constant delivery ofconsumer water usage.

Another object of the present invention is to provide a new and improvedarrangement which conserves water by eliminating diversion to a drainwhen the storage tank is full.

A further object of the present invention is to provide an hydraulicvalving system capable of operating over a wide range of pressure.

Especially in residential applications, one installation of a reverseosmosis system is beneath the kitchen sink. The cleansed and purifiedwater can be dispensed by feeding it to a fixed third faucet, whichoften is in place of a vegetable spray arrangement, with usage primarilylimited to dispensing into the sink basin area. That often isinconvenient in use for several different reasons.

Still another object of the present invention is to provide a new andimproved delivery faucet or outlet valve for use in a reverse osmosissystem and which enables either momentary or continuous water deliveryeither in the sink or over the countertop.

Devices are known for enabling the user to determine the removal rate ofa reverse osmosis membrane by first taking a sample of the raw water andthen manually comparing it to a sample of the permeate water. Normally,the level of total dissolved solids (TDS) is determined by measuringelectrical conductance at a specific temperature, e.g. 72° F. Thesedevices often have been either held by hand or connected to the outputof the reverse osmosis system to allow the user to determine theconductance. In-line conductance monitors usually require that a seriesof switches be set up according to the conductance of input or feedwater. That step typically requires the use of a more sophisticated TDSmeasuring device to determine the percentage of dissolved solids astypically measured by the conductance in micromhos. After the switchesare set up, the device is then installed in the permeate water line tothe outlet of the system.

That approach is lacking in four major areas. First, a serviceorganization usually has to determine the TDS or conductance and programthe in-line monitor for the consumer. Secondly, this type of device canaccumulate a build-up of minerals on its probes projected into the waterflow with that accumulation leading to the result of inaccuratereadings. The third problem occurs particularly when the input watervaries in its conductance by reason of spring rains or other runoffconditions. That is, such an approach cannot offset its reading becauseit has no way of determining the conductance of the feedwater. Thefourth problem occurs when temperature differences exist between theinput and output water conditions.

One objective of the present invention is to provide a way ofdetermining the differential between input and output TDS while keepingthe measurement probes clean during operation and which allows the userto install and use the system without needing an extra TDS measuringdevice.

Another objective is to provide a system which corrects for conductancevariations with the temperature changes as a result of which TDS ismeasured directly.

It is also known to use a monitoring system which automatically comparesfeedwater and permeate product water. This employs probes on the inletside and at the outlet side and is advantageous over the use of only asingle probe monitor which may need recalibration every time thefeedwater temperature and the level of total dissolved solids changes.Such a monitor compares conductivity of the feed and the permeate at thesame time and includes circuitry for calculating the rejection ratio.However, known prior art monitors have suffered from deterioration inperformance by reason of eventual probe malfunction.

A related object of the present invention is to provide a flow monitorin which conductivity probes are maintained in a condition which enablesthem to continue functioning properly.

An ancillary feature of the present invention is the provision ofprogrammed sensing and calculation and the giving to the user of anindication of the condition of one or more components such as the statusof all filters with respect to anticipated ultimate component life andoperational status.

Accordingly, a reverse osmosis system includes a feed water inlet and apermeate outlet together with a squeeze water drain and an outlet valve.A reverse osmosis assembly includes a housing within which is disposed areverse osmosis membrane and which has a feed water entrance, a permeateexit and a concentrate exit. A storage tank has a shell within which abladder is disposed and which has a first port for communicating squeezewater between the outside of the housing and the space within thehousing on the outside of the bladder. A second port communicatespermeate between the housing outside and the space within the bladder.An input valve controls water flow from the feed water inlet to the feedwater entrance in response to the pressure differential between thepermeate and the squeeze water in the tank. A first conduit arrangementdefines a permeate flow path from the permeate exit to the second portof the tank, while a second conduit arrangement defines a concentratepath from the concentrate exit to the first port of the tank. A squeezewater valve is disposed in the concentrate path and operates to controlthe flow of the concentrate between the concentrate exit and that firstport. A proportioning valve is coupled between the concentrate pathupstream from the squeeze water valve and the drain, and a relief valveis coupled between the drain and a concentrate path downstream from thesqueeze water valve. Finally, a regulator is coupled between thepermeate path and the permeate outlet and is responsive to pressuredifferential between the permeate outlet and the permeate path tocontrol permeate flow to the permeate outlet.

In another aspect of the present invention, there is a flow meter whichhas a hollow housing with an interior wall formation that defines acircular raceway. An inlet channel leads from the exterior of thehousing thereinto and opens tangentially into that raceway. An outletchannel leads from the raceway back to the exterior of the housing. Apair of mutually-spaced electrically conductive probes lead from theexterior of the housing insulatingly therethrough to exposure within theraceway. Finally, there is a ball sized to move freely around theraceway when propelled by liquid flowing from the inlet channel to theoutlet channel with the ball being of a material sufficiently abrasiveto remove deposited matter from the electrodes. The ball has anelectrical characteristic which effects an electrical signal when movingthereacross.

Other features of interest are the coaction between components wherebythe regulator responds to increased outlet pressure following closure ofthe outlet valve to close the squeeze valve, the provision in theoverall system of a sediment filter and an impurity filter, theinclusion of check valves at critical points to direct operation of thesystem, the manner of electronic calculation and indication of componentlife status and certain unique valving features. A further feature ofinterest resides in a movable faucet assembly variously operable toproduce either momentary or continuous flow and desirably also includingan air-gap unit for the waste drain.

The features of the present invention which are believed to bepatentable are set forth with particularity in the appended claims. Theorganization and manner of operation of one specific embodiment of theinvention, together with further objects and advantages thereof, maybest be understood by reference to the following description taken inconnection with the accompanying drawings, in the several figures ofwhich like reference numerals identify like elements, and in which:

FIG. 1 is an isometric view of a filter assembly cabinet;

FIG. 2 is a flow diagram of the filter assembly of FIG. 1;

FIG. 3 is a further flow diagram of a valve unit shown generally in FIG.2;

FIG. 4A is an exploded isometric view of a flow meter used in the systemof preceding figures;

FIG. 4B is another isometric exploded view of the flow meter of FIG. 4Abut taken from the reverse perspective;

FIG. 5A is an exploded isometric view of a modular component shown inFIGS. 2 and 3;

FIG. 5B is an exploded isometric view of the component of FIG. 5A buttaken from a reverse perspective;

FIG. 6A is a longitudinal vertical cross-sectional view of a faucetemployed with the filter assembly of FIG. 1;

FIG. 6B is a fragmentary cross-sectional view similar to FIG. 6A butwith certain parts in a different position and with one of those partsin still different position as indicated in phantom;

FIG. 6C is an exploded isometric view of a portion of the faucet shownin FIG. 6A;

FIG. 6D is an exploded isometric view of a remaining portion of thefaucet shown in FIG. 6A together with additional parts of a faucetassembly;

FIG. 6E is a side elevational view of the faucet of FIG. 6A asassociated with an additional mounting and air-gap assembly of FIG. 6Ddepicted in longitudinal vertical cross-section;

FIG. 6F is a top plan view taken along line 6f--6f in FIG. 6E and withthe faucet removed;

FIG. 7 is a flow diagram of a processor used in connection with thefilter system of FIGS. 1 and 2;

FIG. 8A is a partial schematic diagram of the processor to which FIG. 7is directed; and

FIG. 8B is a continuation of the schematic diagram of FIG. 8.

In the drawings which illustrate one specific embodiment of the presentinvention, FIG. 1 is an isometric view of a cabinet 10 in which areformed cavities 11, 12 and 13 which respectively receive cartridgeshousing an inorganic filter, a reverse osmosis filter and a sedimentfilter all of which will be described further hereinafter. Cavities 11,12 and 13 are closed by respective caps 14, 15 and 16 each threaded uponan upper end of the corresponding cavity. Disposed at one end ofassembly 10 adjacent to cavity 13 is a compartment 17 within which ishoused a printed circuit board that carries the electronic components ofa signal processing system and that also has a recessed window 17abehind which is located an indicator or display also carried by theprinted circuit board all as will be discussed hereinafter. Cabinet 10has a base 18 in the hollow interior of which is mounted a module 19 aswell as other components yet to be described. Leading outward fromcabinet 10 are several conduits 19a the purpose of which also will bedescribed hereinafter.

Along with a faucet assembly shown and described in more detail later,the overall specific embodiment constitutes a reverse osmosis systemwhich is organized into a combination of a sediment filter 20, a reverseosmosis filter 22, a valve unit 24, a storage tank 26, an impurityfilter 28, a permeate dispenser or faucet 30 and a signal processor 32all as shown in FIG. 2. While the different components within valve unit24 may each be a separate article hydraulically interconnected in themanner shown in FIG. 3, they preferably are all combined into module 19of FIG. 1. This is advantageous both from the standpoint ofmanufacturing economy but also in terms of ease and time ofinstallation.

Sediment filter 20 is conventional, including a container 36 in which isdisposed a sediment filter media 38. An input coupling 40 receives theraw water from a source 42. An outlet coupling 44 delivers feed waterfrom media 38 and that becomes a feed water inlet 46.

Sediment filter media 38 is in this case a wound polypropylene fiber asis known for use in filtering water derived from municipal water systemsand wells. The media serves to remove dirt particles. While not shown inconnection with the present embodiment, it may be advantageousparticularly in larger systems to incorporate added valving and pipingto permit backwashing of the sediment filter media to flush trappedsediment into a drain. On the other hand, when it is desired to employthe balance of the reverse osmosis system in an application wherein theraw water produced from the source is essentially free from sediment,sediment filter 20 might be eliminated. In that case, the raw watersource is connected directly to feed water inlet 46.

Reverse osmosis filter or assembly 22 includes a housing 50 in which isdisposed a reverse osmosis membrane 52. Housing 50 has a feed waterentrance 54, a permeate exit 56 and a concentrate exit 58. As such, theoperation of reverse osmosis filters is well known. Microscopicinorganic materials contained in the feed water tend to build up on thesurface of membrane 52, while only cleansed water passes through themembrane for delivery from exit 56. A portion of this feed waterconstantly washes over the inlet-side surface of the membrane so ascontinually to remove the build up of the filtered particles and carriesthose particles out of exit 58 as what is conventionally called theconcentrate. The membrane also is flushed when the faucet is actuatedand when concentrate flows to serve as the squeeze water next to bediscussed. A ball-type check valve 60 is located on the outlet side ofexit 58 for the purpose of preventing the flow of concentrate back intofilter 22.

Storage tank 26 has an outer shell 64 within which is disposed aresilient bladder 66. Shell 64 has a first port 68 which communicatesthat which is called squeeze water between the outside of shell 64 andthe space 70 within shell 64 but on the outside of the wall of bladder66. A second port 72 communicates permeate between the outside of shell64 and a space 74 within the wall of bladder 66. In a manner well knownas such in reverse osmosis systems, squeeze water in the form ofconcentrate received from exit 58 of filter 22 is employed to literallysqueeze bladder 66 and thereby force out permeate in the bladder towardthe delivery end of the overall system, in this case faucet 30.

In principle, the squeeze water path could be in communication with theinside of bladder 66 with the permeate path being in communication withthe space within shell 64 but outside bladder 66. In that case, thesqueeze water would be squeezing the stored permeate by expanding thebladder.

Impurity filter 28 has a canister 78 within which is a filter bed 80.Canister 78 includes an input coupling 82 connected to an outlet pathconduit 83 for delivering permeate received by way of an outlet 84 ofvalve unit 24. Canister 78 also has an output coupling 86 carrying flowfrom filter media 80 to outlet valve 30 by way of a conduit 87. Filtermedia 80 is in this instance a known bed of activated carbon particles.That bed removes and treats organic materials. In most carbon filtersfor systems which supply water for human consumption, a special functionis that of seeking to remove that which effects odor and bad taste. Inother industrial applications, impurity filter 28 might use a mediagenerally but significantly of different kind in order to effect theremoval of some particular substances in the raw water that would bedeleterious to the industrial process served. Analogously, when thesystem is going to be used for a purpose other than human consumptionand when organic materials would be of no concern, or for use in anenvironment where the water source was of sufficient organic purity,impurity filter might be eliminated from the overall reverse osmosissystem.

Disposed in the water path at output coupling 44 of sediment filter 20,at what may be viewed as the feed water inlet 46 of the remainder of thesystem, is a flow monitor 90. Similarly disposed in the permeate waterpath at permeate outlet 84 of valve unit 24 is a flow monitor 92 fromwhich the flow path continues in conduit 83 to impurity filter 28. Flowmonitors 90 and 92 will be described in more detail later. It willsuffice for the present to mention that they serve to measure thetemperature and conductivity of the liquid to develop signals which aredelivered to processor 32 by means of respective cables 94 and 96. In aless-preferable alternative, monitor 92 is located between outlet 86 andfaucet 30.

In the description which follows with respect to the interconnectionsamong the different components even within valve unit 24, the word"conduit" is used generically to describe any form of liquid flow path.In actuality for connection purposes, that path may be provided by meansof any of a pipe, hose, tube or rigid channelway in a molded part. To beaddressed now are the details which in the specific embodiment areincluded within valve unit 24.

An inlet valve 100 controls water flow from feed water inlet 46connected by a conduit 102 and leaving valve 100 by way of a conduit 104to supply the feed water to entrance 54 of reverse osmosis filter 22.Inlet valve 100 includes a piston 106 having a large end 108 biased by aspring 110 toward an elastic diaphragm 112. The side of diaphragm 112opposite enlarged end 108 is coupled by a conduit 113 into a permeateconduit 114 leading from port 72 of storage tank 26. The other side ofenlarged piston end 108 is coupled by a conduit 116 into a conduit 118which communicates squeeze water between valve unit 24 and port 68 ofstorage tank 26.

A conduit 119 is connected between permeate exit 56 of membrane filter22 through a check valve 120 poled to pass flow on into a connectionwith permeate conduit 114. Conduits 119 and 114 complete a path frompermeate exit 56 to permeate port 72. Opposite enlarged end 108 ofpiston 106 is a smaller end with a conically shaped nose 121 whichprojects a variable distance into a seat 122 of valve 100. Inlet valve100 controls inletted water flow through membrane filter 22 in responseto the pressure differential between the permeate and the squeeze waterin storage tank 26 at any time.

Another conduit arrangement is composed of the series combination of aconduit 124, a squeeze water valve 126 and squeeze water conduit 118.That arrangement defines a concentrate path from concentrate exit 58 ofmembrane filter 22 to port 68 of storage tank 26. Squeeze water valve126 is operable to control the flow of the concentrate betweenconcentrate exit 58 and port 68. Connected into conduit 124 ahead ofsqueeze water piston 126 is a proportioning valve 127 coupled betweenthe concentrate path upstream from valve 126 and a drain 128. Drainconduit 128 leads to an air gap 130 from which drain flow continues intoan exhaust drain 132. Air gap 130 avoids adverse conditions whichotherwise might occur from siphoning of what effectively is a drain sumpback into the system.

One purpose of proportioning valve 127 is to maintain a fixed ratio ofconcentrate to permeate from membrane filter 22. In this case, the ratioselected is that of eight parts concentrate to one part permeate. Thatratio may change in correspondence with the requirements of theparticular membrane material selected for use. Another function is toensure that water continues to wash across membrane 52 at any time thatpermeate is being generated. For that reason, the proportioning valve isalways open to a degree. This ensures that the membrane surface iscontinually washed and thereby cleaned. The result is extended life ofmembrane 52.

A relief valve 134 is coupled from concentrate path 118 downstream fromsqueeze water valve 126 and feeds into drain 128. Valve 134 serves torelieve pressure from storage tank 26 when incoming permeate flow isfilling bladder 66.

A regulator 140 includes a hollow piston 142 having an enlargedflange-like end 144 and disposed within a surrounding cylinder 146. Aspring 148 inside cylinder 146 urges piston 142 away from adjacentsqueeze water valve 126. A conduit 150 is coupled into the permeate pathof conduit 114 and feeds permeate through a check valve 152 into asmaller hollow end 154 of piston 142. It will be observed that regulator140 is coupled between the permeate path and, ultimately, the permeateoutlet at valve 30.

Regulator 140 responds to the pressure differential between the permeateoutlet flow path and the permeate in bladder 66 to control permeate flowto the permeate outlet. Smaller end 154 of piston 142 opposite enlargedpiston end 144 presents a surface 156 which is exposed to the permeatepressure in conduit 150. A conduit 158 leads from the space withincylinder 146 between the two piston ends 144 and 154 into drain conduit128.

Squeeze water valve 126 includes a piston 160 having one closed end 162aligned with and adjacent to a hollow boss 164 which forms a part ofsmaller end 154 of piston 142. A spring 166 inserted into a well 168formed into the other end 170 of piston 160 is compressed to urge piston160 to a stopped position closest to piston 142. Piston end 170 istapered to define a nose 171 that faces a seat 172.

When squeeze water valve 126 is open, concentrate flows through conduit124 from exit 58 and is delivered into conduit 118 which leads to port68. Upon an increase of permeate pressure in conduit 83, as when faucet30 is partially closed, regulator piston 142 moves against spring 148and toward piston 160 of squeeze water valve 126. As the space betweenpistons 142 and 160 is restricted, permeate flow through regulator 140is reduced. Upon closing of faucet 30, piston 142 pushes on piston 160and begins to close valve 126 to reduce squeeze water flow throughconduit 118 to port 68. With faucet 30 fully shut off, both permeateflow through regulator 140 and concentrate flow through valve 126 becomeblocked.

A pressure responsive switch 176 is disposed at outlet 86 of impurityfilter 28 and is coupled to conduit 87 which carries the permeate tofaucet 30. When a minimum operation system pressure occurs as whenfaucet 30 is fully open, switch 176 closes to send a signal to processor32 by way of a cable 177. An indication is thereby given when the outputfaucet is open. If desired, squeeze water pressure may be monitored inthe alternative or in addition and an indication given to signaldirectly when bladder 66 is full. It will be observed that other suchpressure detection points may be used.

The different components of valve unit 24 preferably are combined intomodule 19 in this case constructed in the manner shown in FIGS. 5A and5B. As will be seen, it provides the various mountings for thosecomponents and includes passageways and channels which serve as thevarious interconnecting conduits shown in FIG. 3. Projecting outwardlyfrom different portions of the assembly are a plurality of individualcouplings to which the various eternal conduits are connected as well asmounting structure.

Module 19 is composed of a stack of rigid molded segments 182, 184, 186,188 and 190 individually separated by respective resilient rubbergaskets 192, 194, 196 and 198. O-ring type gaskets may be used. A line200 which appears on segment 186 is a mold line; that segment does notcome apart after its manufacture is completed.

On the outside of one end segment 182, a coupling 202 connects by way offlow monitor 92 to conduit 83 which leads to impurity filter 28. Acoupling 206 connects to conduit 118 that communicates squeeze waterfrom valve 126 to port 68 of storage tank 26. A coupling 208 in turnconnects to permeate conduit 114 which leads to port 72 of the storagetank. Projecting outwardly from the side of segment 186 are couplings210, 212 and 214 which connect respectively at membrane filter 22 tocheck valve 60 and therethrough to concentrate exit 58, permeate exit 56and feed water entrance 54. At one side of segment 188 is a coupling 216which is connected to conduit 102 and thereby leads to flow monitor 90and therethrough to outlet coupling 44 of sediment filter 20. Finally, acoupling 218 projects outwardly from the other end segment 190 andserves to connect to and serves in part as drain conduit 128.

Successively spaced peripherally around end segment 182 are a pluralityof nubs 220-227 through each of which is an opening as at 228. With theinternal parts yet to be described positioned into appropriate place, aseries of elongated bolts 229 (only one of which is shown) are insertedthrough those openings as well as through all of the correspondinglylocated openings in the similar nubs provided in each of the gaskets andall of the other segments except in the case of the bolts which projectthrough openings 223 and 224 and continue only a short distance beyondthe corresponding openings in segment 188. A plurality of nuts 229adisposed above corresponding washers 229b are threaded on each of theinserted ends of the respective bolts and are tightened for the purposeof clamping together the entirety of the assembly.

Projecting laterally outward from opposing ends of segments 186 arerespective nubs 230 and 232 each of which has an opening therethroughfor the purposes of receiving a screw that assists the mounting ofmodule 19 within cabinet 10 (FIG. 1). Projecting outwardly from endsegment 182 is a lug 233 bifurcated over its outer end portion as shownfor the purpose of also assisting in the mounting of module 19 withincabinet 10.

Each of couplings 202, 206, 208, 216 and 218 is in the form of a hollowcylinder the interior wall of which is necked down in three successivesteps 234, 236 and 238. A brass ring 240 is plugged into the outeropening to seat against step 234 beyond which is an O-ring 242 thatseats against step 236. A generally cylindrical retainer 244 has acollar 246 from which laterally-inset fingers 248 depend longitudinallyto respective laterally offset tips 250 inwardly from which projects asharp-edged metal cleat (not shown). Retainer 244 is moved into placewithin ring 240 as tips 250 are forced therethrough. On installation,the connecting hose which serves as a conduit is inserted through collar246 past the cleats and sealingly through O-ring 242 until its free endseats against step 238. Upon any attempt to pull out that hose end, thecleats dig into the exterior surface of the hose and resist suchwithdrawal.

Formed into the outer surface of segment 182 as shown is a square well255 which has an opening in its bottom and into which may be inserted apressure-responsive microswitch 256 that has leads (not shown) whichelectrically connect to microprocessor 32. Screws 262 are insertedthrough corresponding openings in a cap 266 to secure cap 266 onto thetop outer surface of end segment 182. Switch 256 has an actuatingplunger 268 which, upon assembly, rests against a solid area of gasket192 the other side of which area communicates with an opening 270 insegment 184. Opening 270 communicates internally of segment 184 toanother opening 272 from which a small channel 274 in turn leads to whatis an interior space or chamber 275 which is within inlet valve 100 andfrom which conduit 116 emerges (FIG. 3). It may be observed that opening270 is surrounded by a recess 276 in order to permit pressure variationin opening 270 to cause a limited degree of flexure of that area ofgasket 192.

As discussed above but not shown in FIGS. 2 or 3, switch 256 may beincluded for the purpose of enabling processor 32 to respond also tosqueeze water pressure. However, it presently appears that thejust-discussed provisions for switch 256 are unnecessary. The inclusionof switch 176 at the outlet side of impurity filter 28 adequately servesthe purpose. Switch 176 preferably may include a pressure responsivepiezoelectric transducer as may switch 256 if used. Preferably, ahydraulically-operated electromechanical switch is used for switch 176.

The immediately preceding discussion serves to illustrate how, when onecompares a portion of the structure in FIGS. 5A and 5B to the flowdiagrams of FIGS. 2 and 3, different fluid flow or pressure transmittingpaths called for by the flow diagrams can with careful study be foundwithin the different openings, cavities and related formations that areillustrated in FIGS. 5A and 5B with respect to the opposing sides ofeach segment and the shapes of the different gaskets. Thus, it becomesunnecessary to describe all of those paths in complete detail. Thestructure illustrated in the drawings is sufficient to enable the makingand using of valve unit 24.

Aligned over coupling 208 is an irregularly-shaped well 280 into theinterior side of segment 182. Seated into well 280 is an insert 282 witha small opening 284 through the center of its circular portion. A finger286 presses gasket 192 over opening 272 and channel 274 in segment 184.A tab 288 has an upstanding hollow boss 290 which fits into a recessedopening 292 of segment 184 after passing through an opening 294 ingasket 192.

It may be observed that there is a large continuous area 296 of gasket192 which overlies opening 284 in insert 282. In use, area 296 serves asdiaphragm 112 described above with respect to FIG. 3. Atop diaphragmarea 296 is the enlarged end 108 on one end of piston 106 surrounded byspring 110. Seated on the other end portion 300 of piston 106 is anO-ring 302. End portion 300 is axially recessed at 303 and the areasurrounding the recess is tapered to define nose 121. Nose portion 300is disposed within chamber 275 so that nose 121 projects through segment184 and into a well 306 within which are a circumferentially-spacedseries of longitudinal segments 308. Inserted within segments 308 is awasher 310 having a beveled entrance that serves as seat 122 for nose121.

Except when nose 121 is pressed by diaphragm 112 so as to close againstseat 122, water from sediment filter 20 is able to flow through coupling216, a hole 311 in gasket 196, an opening 312 in segment 186 and a sideof an opening 313 in gasket 194 after which it continues through theslots between segments 308 and finally emerges from the central openingin washer 310 in order to supply feed water through coupling 214 fordelivery to membrane filter 22.

An opening 320 in gasket 192 provides a permeate path from incomingpermeate coupling 212 by way of an opening 321 in gasket 194 and throughcheck valve 120 to conduit 114 by way of outgoing permeate coupling 208.Valve 120 is in the form of a hollow cylinder 322 open at one end andclosed at the other end by a snout 324 which is composed of aspace-opposed pair of lips 326 that resiliently open for passage ofwater out of the lips but which close tightly against the flow of waterin the opposite direction. Valve 120 seats in a wall 328 formed insegment 184. An opening 330 in gasket 192 communicates between squeezewater coupling 206 and an opening 332 in segment 184.

A larger opening 334 in gasket 192 surrounds an end-slotted hollow boss336 which leads from permeate coupling 202. Cylinder 146 is definedwithin segment 184 and surrounds hollow piston 142 of regulator 140. Asdiscussed earlier, piston 142 has enlarged end 144 and smaller end 154that forms hollow boss 164, all together with compression spring 148.Enlarged end 144 seats an O-ring 338. Another O-ring 340 is seated onthe central portion of piston 142 near smaller end 154.

At the interior end of cylinder 146 is a smaller bore 350 which receivesboss 164. Bore 350 communicates through a well 352 to a bore 354 whichserves as a stop for piston 160. Piston 160 carries an O-ring 360 nearits closed end 162 and at its other end 170 is hollowed out to definewell 168 and shaped to define a peripheral bevel which serves as nose171. Piston 160 projects into and slides within a bore 364 in segment186. Seated within well 168 and inserted through nose 171 is one end ofspring 166. Spring 166 projects through a washer 365 formed like washer310 to have one side of its central opening beveled so as to define seat172. The other end of spring 166 seats on a hollow boss 368 on segment188.

An opening 372 in gasket 196 communicates with the slots between aplurality of circularly-spaced segments 380 located in a well 382. As aresult, there is a concentrate flow path from coupling 210 through thecentral opening in washer 365, opening 372 in gasket 196 and an opening374 in segment 188. A concentrate path also extends from an opening 384in gasket 194 through opening 332 in segment 184, opening 330 in gasket192 and to squeeze water coupling 206. More detail is set forthhereinafter.

Other end segment 190 includes a large dome 400 near one end and a smalldome 402 near its other end. The interiors of both domes 400 and 402communicate with drain coupling 218. A closure strip 404 hascorresponding smaller domes 406 and 408 that nest into domes 400 and402. Domes 406 and 408 each have respective openings 410 and 412 whichlead into the interiors of domes 400 and 402. A notch 414 in the edge ofstrip 404 also establishes communication to drain coupling 218 through ahole 418 in gasket 198, an opening 420 in segment 188, a hole 421 ingasket 196 and ultimately into cylinder 146 of regulator 140 so as toprovide the drain connection of conduit 158 in FIG. 3.

Relief valve 134 includes a hollow cylinder 422 closed at end 424 inwhich there is a slot 425 and which is open at the other end to receivea compression spring 426. Cylinder 422 is generally circular but has acircumferentially-spaced series of ribs 427 on its exterior surface.Cylinder 422 with spring 426 contained therein is inserted into a bore428 defined within dome 408. As indicated earlier, relief valve 134ultimately is coupled between the drain and the concentrate pathdownstream from squeeze water valve 126 that serves to bleed pressurefrom tank 26 as the permeate flow fills bladder 66. Cylinder 422 is onlya loose fit and never makes a complete seal.

Within cone 406 is a sleeve 430 in the form of a hollow truncated cone.Sleeve 430 is seated onto a solid generally-cylindrical body 434 on theexterior surface of which is a thread-like spiral channel that in useserves as a capillary tube 435. Sleeve 430 together with body 434 serveas proportioning valve 127. It will be recalled that it is valve 127which establishes an eight-to-one concentrate-to-permeate ratio thatremains fixed. Capillary tube 435 allows water to flow across themembrane for cleansing whenever permeate is being generated.

Cylinder 422 projects slightly outward from strip 404 through an opening438 in gasket 198 so as generally to rest against the end of flowpassage 374. A larger opening 440 in gasket 198 permits the larger endof body 434 to protrude into a well 442 on segment 188 and from thebottom of which an opening 443 begins a path through an opening 444 ingasket 196 and effectively back to concentrate conduit 124. This path isalways open, by-passing piston 160 and seat 172.

An opening 445 through segment 188 communicates through a hole 445a ingasket 196 eventually with coupling 206. This passage receivesconcentrate from membrane filter 22 for delivery through opening 374. Itfurther includes an opening 445b and an opening 445c in communicationwith opening 384. Mounting pins 446 and 447 on strip 204 project throughcorresponding openings 448 and 449 of gasket 198 with pin 446 seatinginto a hole 450 in segment 188.

Check valve 152 is constructed like valve 120 and seats in recess 292 insegment 184. Other holes and openings in the segments and gaskets andwhich are visible in the drawings will be observed to align with thedifferent holes and openings that have been discussed in detail.

A specific physical embodiment of faucet or dispenser 30 is shown inFIGS. 6A-6F. A faucet 460 includes a lower housing 462 atop which sitsan upper housing 464 from which emerges an operating lever 466.Projecting to one side of the normally vertical handle 472 formed bylower housing 462 is an opening 474 in which one end 476 of a preferablyflexible hose 478 is disposed. The other end 479 of hose 478 is insertedinto a channel 480 through a plug 481 disposed on top of a connectingtube 482 inserted within a bore 483 defined in handle 472.

Running centrally through plug 481 is a passage 484 within which slidesa piston 486. The passage is sealed by an O-ring 488 assembled on apiston head portion 496. Disposed across the bottom of plug 481 is awasher 489 which forms a seat 490 against which a valve body 492 formedon piston 486 is urged upwardly by a compression spring 494 disposedbetween a shoulder 495 formed internally of tube 482 and a flat 493 onthe bottom of valve body 492.

Projecting downwardly within opposing sidewalls 497 of lower housing 462from upper housing 464 is a spaced pair of bifurcated ears 498. Lever466 is positioned in a slot 500 formed centrally into the end of upperhousing 464 opposite outlet 474. A pin 502 is disposed through lever 466and is of sufficient length to rest within the bifurcated forks 504 ofears 498 as well as being captivated by the upper sidewalls of lowerhousing 462 upon assembly.

Lever 466 has an inwardly projecting cam 506 which engages piston head496. Cam 506 has two successive facets 510 and 512. Swinging of lever466 serves to select which facet is brought into contact with head 496,and that forces piston 486 to be depressed and open valve body 492 fromseat 490. In addition, when upper normally level surface 514 abovepiston 484 is depressed by operation of the user's finger, head 496 ispushed downwardly to open valve 492 as shown in FIG. 6B. Alternately,lever 466 may be swung down to engage facet 510 and momentarily open thewater flow path as shown in phantom for lever 466a. When the force isremoved, valve body 492 closes against seat 490. Swinging lever 466fully up as shown in phantom for lever 466b causes facet 512 to lockpiston 486 in a position so that valve 492 remains open. When lever 466is returned to the position in FIG. 6A, a spring 515 seated on ashoulder 515a biases piston head 496 toward facet 510 which, in turn,allows spring 494 to bias valve body 492 into a closed position.

When not being held in the hand, the lower end portion 516 of handle 472is seated against a centrally apertured downwardly-concave crosswall 518within the bore 520 of a base 522 as shown in FIG. 6E. An outwardlyprojecting longitudinal rib 524 is defined on the sidewall of the well526 formed in the top of base 522 by crosswall 518. A longitudinalgroove 528 on end portion 516 seats on rib 524 when handle 472 is placedinto well 526, locking faucet 460 against turning.

A flexible hose 530 is connected onto a barb 531 formed on the bottom ofconnecting tube 482 so as to convey water toward valve 490, 492. Barb531 is formed, as shown, to permit the end of hose 530 to be pushed onafter which it cannot be pulled off with normal force applied. Onemerging downwardly through an opening 516a in handle 472, hose 530 isconnected to a hose 532 through a union 533 (not shown in FIG. 6e). Theother end of flexible hose 532 is in this instance coupled as in FIG. 2to receive the output of impurity filter 28 from the outlet of switch176 at coupling 86. As an alternative, hose 530 could connect directlyto the outlet of pressure switch 176. An aesthetically attractive collar522a is mounted at the top of base 522.

As shown in FIGS. 6D and 6E, the lower end of base 522 is seated overthe top of an air-gap unit 534 which has a platform 534a from whichdownwardly projects an externally threaded hollow tube 534b. Upstandingfrom platform 534a is a hollow boss 534c. Flexible hose 530 leadsdownwardly from faucet handle 472 through boss 534c, tube 534b, a gasket535, a washer 536 and a nut 537 on into cabinet 10 wherein hose 532becomes conduit 87 of FIG. 2 and connects through switch 176 to permeateexit 86. In a typical installation at a kitchen sink, tube 534b projectsdownwardly through the so-called third-faucet hole in the sink rim withthat rim being sandwiched between gasket 535 and washer 536 by nut 537threaded onto tube 534b.

Also upstanding on platform 534a is a baffle 538 which curves outwardlyfrom its two ends to define together with an external portion of boss534c part of a basin 539. The upper portion of a nipple 540 projectsupward through platform 534a and opens into the bottom of basin 539. Thelower end of nipple 540 connects to a flexible drain hose 132a whichleads downwardly through nut 537 and serves as exhaust drain 132 of FIG.2.

The upper portion of another nipple 541 projects upward through platform534a and connects to the bottom of a rising flexible tube 542. Avertical divider wall 543 spans the distance from the side of boss 534cto baffle 538 and completes the definition of basin 539. The upper endportion of pipe 542 is assembled to a 90° barb 544 which is orientedreentrantly so that its bottom opening or outlet is spaced above thebottom of basin 539 and thereby forms air gap 130 of FIG. 2. Thus, thelower portion of nipple 541 connects to a flexible hose 128a that leadsdownwardly through nut 537 and in FIG. 2 becomes drain conduit 128. Itmay be observed that the bundle of hoses 19a as shown in FIG. 1 becomethe hoses discussed with respect to FIGS. 6A-6F together with anotherhose which leads to the raw water source (42 in FIG. 2).

FIG. 7 is a flow diagram of processor 32. While that flow diagram isherein basically implemented by the use of off-the-shelf individualcomponents, it will be appreciated that all or most components exceptfor a battery, a display and the input and output probes may beincorporated into a dedicated chip.

As shown, an input probe 550 is defined to include flow monitor 90 whichserves as a flow meter and a temperature sensor. An output probe 552 isdefined to include flow monitor 92 which also serves as a flow meter anda temperature sensor. Temperature is measured because, for example,water in storage tank 26 could be at 80° F. while incoming water in thewinter could be 45-50° F. To determine the TDS from conductivity,temperature is herein normalized to 72° F. Not normalizing conductivityto a given temperature would cause extreme errors in measurement of TDS.

Respective input and output analog temperature signals are fed overrespective leads 554 and 556 to an analog selector 557. In discussingthis flow diagram, the terms "lead" or "connect" are used to describewhat may be either a single or a multiple-wire connection. That is, thelines drawn represent signal paths.

A battery 558 supplies power for the entire system. Voltage reference559 is connected to selector 557 by lead 560. A control ground systemconnects from a terminal 561 to all circuit devices except as separatelyshown or later described with respect to FIGS. 8A and 8B. Leads 562 and553 connect one probe terminal in each of flow monitors 90 and 92 torespective terminals A and B of a probe selector 564.

A lead 565 connects probe selector 564 to one terminal of an AC to DCconvertor 566. Leads 567 and 568 connect a second probe terminal in eachof respective flow monitors 90 and 92 in common through a lead 570 toanother terminal of convertor 566. By means of leads 571 and 572 theoutput of a one kHz AC simulation circuit 573 is also connected to thesame terminals of converter 566 as are respective leads 567 and 568.Convertor 566 is connected by a lead 574 through a noise filter 575connected in turn by a lead 576 to a DC level amplifier 578. Amplifier578 is connected by a lead 579 to analog selector 557.

Probes 550 and 552 as selected at any given time yield a signal fromflow monitors 90 or 92 which is in the form of a spike, and that spikeis fed from filter 575 over a capacitor 580 to a spike detection circuit582. The detected spike signal is then fed over a lead 584 to apulse-shaping circuit 586 which transforms the spike into a more squarepulse that is then fed by a lead 588 into a microcomputer 590.

The signal level from amplifier 578 represents a conductivity outputsignal which is fed to analog selector 557. The output chosen by analogselector 553 is fed over a lead 592 to an A-D convertor 596 forconverting analog signals to representative digital count values thatare fed to computer 590 by a lead 592 and leads 622-627 describedfurther hereinafter. Analog selector 553 is controlled by signals fedfrom microcomputer 590 over leads 598 and 599. Another signal frommicrocomputer 590 is fed over a lead 600 to an audio circuit 602 for thepurpose of developing an alerting sound. A further initiating signalfrom microcomputer 590 is fed over a lead 604 to AC simulation circuit573.

Simulation circuit 573 feeds an alternating current signal to probes 550and 552 so that they are actuated alternately. That AC signal also isfed to convertor 566 so as to cancel the same AC signal coming back fromthe probes. Consequently, the signal fed to noise filter 575 is composedonly of the sensed direct current signal upon which the spike issuperimposed.

To control the segments in a display 620, a continuously switchingmultiplex signal is fed to display 620 over respective leads 610-617.A-D convertor 596 is sequenced by the voltage on a plurality of leads622-629 to cumulatively increase the compare voltage relative to thevoltage from selector 557. That is, it is the difference between theselector output voltage and the compare voltage which is fed tomicrocomputer 590 over lead 592. When the compared voltages are equal,the voltage on lead 592 will toggle and the binary representation of thevoltage will be read.

The negative terminal of battery 558 is connected by a lead 632 tomicrocomputer 590 and also to ground. A lead 633 connects the positiveterminal of battery to microcomputer 590. A lead 634 returns alarm 602to the negative battery terminal. A signal from microcomputer 590 by wayof a lead 635 operates a ground switch 636. Switch 636 serves to disablemost of the different components of processor 32, and thus most of thestages shown in FIG. 7, when the processor is on standby or hold. Uponreceipt of a signal from pressure switch 176 at permeate outlet 86 (FIG.2), ground switch 636 is actuated by the signal fed by a lead 635 frommicrocomputer 590. Thereupon, power is applied to almost all circuits orstages by grounding of control ground or terminal 561 and of analogselector 557 by way of a lead 637.

Before delving into details of processor 32, attention will next begiven to a preferred structural approach for input and output probes 550and 552. As will be seen in FIGS. 4A and 4B, flow monitor 90 or 92 isfirst of all a flow meter and has a hollow housing 650 composed in thiscase of a top half 652 and a bottom half 654. The interior wall of theassembled housing is formed to define a circular raceway 656. An inputchannel 658 leads from a hose coupling 660 on the exterior of housing650 and thereinto with channel 658 opening tangentially into raceway656. An outlet channel 662 leads from raceway 656 to an outlet coupling664 on the exterior of the opposite side of housing 650.

A pair of mutually-spaced electrically conductive probes 666-667 leadfrom the exterior of housing 650 insulatingly therethrough. In thiscase, bottom portion 654 and the top portion 652 are molded of a rigidplastic which is an insulating material. The ends of probes 666-667project into the raceway just sufficiently to have physical contact witha ball 668 moving across the probe inner ends. Ball 668 is sized to movefreely around raceway 656 when propelled by liquid flowing from inletchannel 658 to outlet channel 662. Ball 668 is of a materialsufficiently abrasive to remove deposited matter from the inner ends ofprobes or electrodes 666-667. Moreover, ball 668 has an electricalcharacteristic which effects an electrical signal in moving thereacross.The electrical signal may be effected merely by the conductivitycharacteristics of ball 668. Preferably, ball 668 has a dielectricconstant significantly higher than that of water so that its movingacross the inner ends of probes 666-667 creates a spike-shaped changesuperimposed on the direct current conductivity level. This allowscalculation in processor 32 of flow rate and total flow.

Outlet channel 662 might lead to any point around raceway 656, but itsentrance 670 preferably lies generally along the axis of raceway 656 butas shown is slightly offset from that axis. A downward and axiallyprojecting nub 669 on top portion 652 serves to direct water downwardlyand into entrance 670. This ensures that ball 668 rides near the bottomof raceway 656 so as to move physically across the inner ends of probes666-667. That effects a cleaning action of probes 666-667 in order toremove all build-up of materials which tend to deposit thereon from theliquid which in the present system is water that includes traces ofsedimentary materials. Outlet coupling 664 is made the same as couplings202, 206 and those others so as to grip and retain the inserted endportion of a hose.

Adjacent to probes 666-667 on the inner side of top portion 652 is adepression the bottom of which adjacent to raceway 656 is extremely thinso as to be at essentially the same temperature as that of the waterflowing in the raceway. A thermistor 674 is seated in that depressionfor the purpose of developing a signal level representative of thetemperature of the flowing liquid. Accordingly, thermistor 674 isconnected electrically to processor 32 by a two-wire cable 676.

Returning now to a more detailed discussion of the operation ofprocessor 32, FIGS. 8A and 8B together represent a schematic diagram ofa specific embodiment preferred for use in implementation of the flowdiagram of FIG. 7. FIG. 8A continues onto FIG. 8B with the arrowheads atthe right of FIG. 8A and denominated with the letters a-k indicatingthat each such lead continues on to the correspondingly lettered leadsat the left side of FIG. 8B. At the left side of FIG. 8A there are aseries of standard symbols that indicate female pin connections in aconventional multi-wire connector collectively indicated by the number700. Each of the individual pins in that connector is assigned acorresponding pin number selected from 1 through 12. In contrast withthe leads shown in FIG. 7 which indicated signal paths, all leads shownin FIGS. 8A and 8B represent a single conductor which may be either aline printed on a circuit board or an individual wire.

In connector 700, pin 1 connects to the negative of terminal battery558, while pin 2 connects to the positive terminal of that battery. Pin1 and pin 3 are connected to a common ground 702 represented by aconventional multi-bar arrowhead. Whenever that multi-bar ground symbolis used throughout FIGS. 8A and 8B, it means a connection directly tothe negative terminal of battery 558. Pin 2, on the positive batteryterminal, connects through a diode 704 to a positive supply terminal 706represented by a narrow-based arrow. Whenever throughout FIGS. 8A and 8Ba component has a connection represented by that narrow-based arrow, itmeans a connection to the positive battery terminal by way of diode 704.Protection against component injury from battery reversal is provided bydiode 704.

Pin 1 of connector 700 is further fed to the source terminal of aFetlington transistor 710 which has its drain terminal 712 connected toa control ground 714. That control ground 714 is represented by awide-based arrowhead. Whenever throughout FIGS. 8A and 8B thatwide-based arrowhead is depicted, that means a connection directly tocontrol ground 714. The gate terminal 716 of transistor 710 is connectedto a pin 4 of a microcomputer unit 720. In this case, microcomputer 720is a type NEC7507MCU with the different pin numbers depicted around itsborders corresponding to the pin numbers assigned to that unit by themanufacturer.

A capacitor 717 is connected between terminal 706 and common ground 702,while another capacitor 718 is connected between terminal 706 andcontrol ground 714. Those capacitors serve to dampen any interferencewhich may develop from external sources or even from internal sourcessuch as the microcomputing unit. In conventional terminology, terminal706 corresponds to the legend "VDD" often employed in connection withmicroprocessors and other integrated circuits.

Transistor 710 is the active device controlling power switch 636 of FIG.7 by means of a control signal received from unit 720 so as to connector disconnect control ground 714 from battery negative terminal ground702. When transistor 710 is in its open state between its source anddrain, all of the different circuit components returned to ground by wayof control ground 714 are deactivated.

Pressure switch 176 is connected across pins 3 and 4 of connector 700with pin 3 being connected to common ground 702. Pin 4 is connected atone end of a pull-up resistor 732 to keep a positive bias on pin 23 ofunit 720 until the pressure switch is closed to short pins 3 and 4,thereby applying a negative or neutral bias to the processor.

A test point 719 is indicated between pin 2 and diode 704. Other suchtests points are indicated in the same way at various places throughoutFIGS. 8A and 8B and need not be mentioned further.

Pins 5 and 7 externally connect respectively to the thermistors in flowmonitors 90 and 92. Pins 6 and 8 individually connect to respectiveopposite sides of each of those thermistors, returning those oppositesides to control ground.

Pins 5 and 7 internally connect respectively to pins 6 and 7 of ananalog multiplexing and sampling device 736. In this instance, device736 is a type MC14097B which has its different pin numbers indicatedalongside. It will be observed that device 736 in part serves thefunction of analog selector 557 in FIG. 7. Pin 5 of connector 700 alsois connected between resistors 740 and 741 in turn connected in seriesbetween positive terminal 706 and the control ground so as to serve avoltage divider. In the same way, pin 7 is also connected to such avoltage divider composed of resistors 742 and 743. The voltage dividerssupply the necessary static operating current required for operation ofthe thermistors in flow monitors 90 and 92, along with allowing thecorrect current to be obtained through the thermistor.

Pin 9 of connector 700 externally leads to one probe electrode in flowmonitor 92, while pin 10 externally leads to the other probe electrodein that monitor. Similarly, pin 11 externally leads to one probeelectrode in flow monitor 90 and pin 12 externally leads to the otherprobe electrode in that monitor. Pins 9 and 11 of connector 700 areinternally connected respectively to pins 22 and 23 of device 736. Aprobe select signal is conveyed from pin 1 of device 136 through aresistor 746, an inverter 748 and another resistor 750 to both of pins10 and 12 on connector 700 that lead individually to an electrode ineach of the flow monitors. A one kHz signal is fed from pin 24 ofmicrocomputer unit 720 through an inverter 752, inverter 748 andresistor 750 also to pins 10 and 12 of connector 700.

The junction between inverters 748 and 752 is connected back throughresistor 746 to a diode 754, and the junction between inverter 748 andstill another inverter 756 is connected back through a diode 758 withthe other sides of each of diodes 754 and 758 being connected in commonthrough a resistor 760 and a resistor 762 to the minus input of anoperational amplifier 764. A capacitor 766 is connected between controlground and a junction between resistors 760 and 762. A resistor 768 alsois connected from the junction between resistors 760 and 762 to controlground. The other input of operational amplifier 764 is connected to ajunction in a voltage divider composed of resistor 770 and potentiometer772 with that junction also being connected to pin 5 of device 736.Potentiometer 772 is used for calibration of current and current returnlevel. A feedback resistor 774 shunted by a capacitor 776 is connectedbetween the output of operational amplifier 764 and its input connectedto resistor 762.

Accordingly, the one kHz alternating current used to prolong the life ofthe electrodes in the flow monitors is obtained in the form of AC pulsesfrom terminal 17 of device 736, those pulses being fed into a series ofinverters with the output from the first inverter fed into the secondand its output fed into a third. It should be noted that the output ofthe third inverter is not connected to anything. It is used to keep aneven loading on the various circuits. The outputs of inverters 748 and752 drive the probe electrodes through respective resistors. In essence,the one kHz frequency was chosen because of the time base needed incomputer unit 720 and the resolution needed in order to determine flowrates up to three gallons per minute. Diodes 754 and 758 function assteering diodes to direct the composite signal toward operationalamplifier 764 as well as to a pulse amplification circuit which includesanother operational amplifier 776. Resistor 760 serves to lower theimpedance on the output side of diodes 754 and 758 and assists inobtaining a higher signal-to-noise ratio. Moreover, resistor 760together with capacitor 766 serve also to filter noise.

It will be observed that with respect to the flow diagram of FIG. 7 thefunction of simulation circuit 573 is provided by device 736 as is thefunction of probe selector 564. Diodes 754 and 758 together act asconvertor 566 with the resistors and capacitors mentioned functioning asnoise filter 575. Moreover, operational amplifier 764 serves thefunction of DC level amplifier 578 in FIG. 7 and its output is connectedto pins 8 and 9 of analog device 736.

Operational amplifier 764 with its feedback resistor 774 averages outthe spikes produced by the ball traveling between the electrodes in themonitor assemblies. The pulse of spike signal arriving through diodes754 and 758 and resistor 760 is coupled over a capacitor 780 and througha resistor 782 to the minus input of amplifier of 776 the other input ofwhich is returned to control ground. A feedback resistor 784 isconnected from the output to the minus input of amplifier 776. It may benoted that amplifier 776 is operated in the inverting mode as isamplifier 764.

If found to be necessary, a capacitor may also shunt feedback resistor794 in order better to filter out the one kHz signal along with noisethat may be generated from external sources. To further enhance theamplification and lower the impedance, a resistor 786 is connectedbetween control ground and the junction between capacitor 780 andresistor 782. Amplifier 776 is operated at a comparatively low gain soas to contribute to significant amplification only of the fast changingportion of the signal received from the probe electrodes. The outputfrom amplifier 776 is fed through a series of inverters 790, 791 and 792from which the pulse signal is fed to pin 22 of microcomputer unit 720.The combination of inverters serves to further shape the flow ratepulses for use by unit 720, corresponding the function of pulse shaper586 in FIG. 7.

Voltage reference 559 of FIG. 7 is implemented as shown in FIG. 8B byinverting operational amplifier 794 having a feedback resistor 796 withits minus input being returned to control ground through a resistor 798.Its plus input is connected through a resistor 800 to the positivevoltage source as well as through a reference diode 801 to controlground. The output of amplifier 794 connects to pin 4 of analog device736.

The output from pin 17 of device 736 is fed to the plus input of acomparator 802 the output of which is fed to microcomputer 720 at itspin 25. The other input of comparator 802 is connected to an output pin10 of an A-D convertor 804. Sampling input pins 2-9 of convertor 804 areindividually connected respectively to pins 35-38 and 31-34 ofmicrocomputer unit 720. Pin 1 of convertor 804 is returned to unswitchedcommon ground. Thus, the function described earlier with respect toconverter 596 in FIG. 7 is the same except that the comparison therementioned is specifically shown in FIG. 8B as comparator 802. Convertor804 will accumulate voltage until it reaches a sample voltage at whichtime the comparator changes states and stops microcomputer 720 fromincrementing converter 804.

Display circuit 620 of FIG. 7 also appears in FIG. 8B and preferably isin the form of a twisted nematic liquid crystal display for providingvisual information to the user. It's eight segments are connectedindividually to the different ones of pins 14-17 and 27-30 ofmicrocomputer unit 720. The latter switches the backplane of the displayand different segments at approximately twenty hertz. The segments areactivated by inverting the signal to the backplane and the segments. Thetwenty hertz frequency was chosen for clarity of the segments as viewedthrough its polarizer.

Alarm 602 of FIG. 7 as shown in FIG. 8B includes a piezoelectrictransducer 810 having one plate 812 connected to common ground and itsopposite plates 814 connected to pin 5 of microcomputer 720.

Pin 19 of microcomputer 720 is connected over a capacitor 820 to commonground and also through a resistor 822 to pins 19 and 21. This governsthe clock in unit 720 to generate a frequency of 200 kHz. Pin 18 of unit720 is connected to the junction between a capacitor 824 and resistor826 with the other end of resistor 826 being connected to common groundand the other side of capacitor 824 being connected to the positive DCsupply. All of microcomputer pins 1, 6, 7, 8, 9, 26 and 39 are connectedto common ground while pins 2, 3 and 40 remain unconnected.

The functions provided by the flow diagram of FIG. 7 and the specificcircuitry of FIGS. 8A and 8B lend themselves to varied program features.One feature in the program is that of a self check. When the batteriesare installed in the system, microcomputer unit 720 goes through aself-check routine which includes a display test wherein all displaymodes are sequenced, the audio alarm is sounded and the battery voltageis checked for being above a prescribed minimum.

After a new membrane filter has been installed, the system will displaynothing after the foregoing self-check routine until about four gallonsof water has been drawn from the system through faucet 30.

To protect the consumer against consuming the filtered water until allpreservatives have been washed off the membrane, an "OK" segment on thedisplay is not activated until that amount of gallonage has passedthrough the system. This function is automatically reactivated wheneverthe membrane filter is replaced.

There is a check of membrane status and conductivity measurementprocedure. Input water conductivity and temperature are compared tooutput water conductivity and temperature. When the dissolved solidsremoval falls below about sixty-seven percent, display 620 indicatesimproper status. That comparason uses ten-sample averaging to assurethat the reverse osmosis membrane is bad. When that is determined,accoustic alarm 602 is sounded and a "replace filter 2" is displayed.The alarm is reset when the removal rises above sixty-seven percentwhich is accomplished by replacing the membrane at which time the systemgoes back into the membrane flush mode discussed above.

There also is sediment filter status and flow rate measurement. The flowrate is measured by counting the revolutions of the ball in the flowmonitor during a set period of time in order to calculate the flow rate.When that flow rate drops below about 0.25 gallons per minute, alarm 602is sounded and a "replace filter 3" appears on display 620. When theflow rate rises above 0.25 gallons per minute, alarm 602 is reset. Toprevent fluctuations in water pressure from giving false alarms, thisdetermination also is averaged over a nine-sample period.

Another determination is made with respect to carbon filter status andtotal flow measurement. The total flow through the system is measured byincrementing a register each time the ball passes the probe electrodesin the flow monitors. When the flow reaches about five-hundred gallons,alarm 602 sounds and display 602 sequences between "replace filter 1"and "replace B". The latter is because when the carbon filter isreplaced the battery is also replaced. Alarm 602 is reset by replacingthe battery. As indicated, the battery should be changed each time thecarbon filter is replaced. The battery (which may be multiple batteriesconnected together) is checked at the time of installation to be surethat enough energy is left to continue until the next carbon filterchange. If the battery is above a preselected voltage with ground switch636 activated, the battery has enough life left until that next filterchange. This function is used to prevent the user from putting badbatteries in the system. If the batteries are weak at the time ofinstallation, the unit will lock up the display on "replace B" and alarm602 will sound.

There is a possibility that valve unit 24 will cycle at times when thefaucet has not been turned on. The system described distinguishesbetween a normal cycle and a false cycle period. This is accomplished bychecking output monitor 92 of the system for flow before continuing toprocess the signals provided by the valve unit.

As explained previously, microcomputer unit 720 disconnects the controlground and thereby shuts down most of the circuitry when it is waitingfor water to be drawn from faucet 30. That conserves considerable power,lowering current drain from the battery to as little as about tenmicroamperes. Microcomputer unit 720 also controls all switch debounce,delays for retest and switch state monitoring. As noted, a one kHzsignal is provided to the probe electrodes by analog selector andmultiplexing device 736 under control of microcomputer 720. Thisprevents the plating of minerals out of the water onto the probeelectrode ends. The nature of the material from which the flow monitorballs are made also contributes to keeping the probe electrodes clean.

During operation, the water flows around the outside of the inlet valveseat and then passes through a hole in the center of that seat toentrance 54 of reverse osmosis filter 22. When storage tank 26 is fullof permeate, bladder 66 is expanded to the inner wall of the tank. Whenthe permeate is continuing to fill, the pressure in the storage tankincreases. Inlet valve 100 is sized so that when the storage tankreaches a desired shutdown pressure that pressure closes the inlet valveby means of the application of pressure upon diaphragm 112. After suchshutdown, membrane output pressure is relieved through the proportioningvalve. Check valve 120 holds pressure on conduit 114 to keep piston 106closed. At this time, water through the remainder of the system isstopped until the consumer dispenses water from the faucet at which timethe permeate tank pressure decreases enough to allow diaphragm 112 topermit the inlet valve to hold open.

It will be observed that the remainder of valve unit 24 is used toinsure delivery of the water from the tank to the faucet at a constantdelivery rate. With the squeeze water and regulator pistons open, theconcentrate flows into the tank and squeezes the outside of the bladderto force the permeate water to the faucet. The regulator controls theflow to the faucet to enable action of valve unit 24 over a large rangeof pressure variation. Squeeze water valve opens or closes the flow tothe squeeze side of the tank as actuated by the regulator. A stop withinvalve unit 24 prevents the squeeze water valve from retracting too far.

As the permeate flows from pressure tank 26 for delivery from thefaucet, it enters the small side of the regulator piston and flowsthrough the center of the piston. With increase of pressure on thelarger diameter end of regulator 140, its piston begins to move. As itmoves, however, the clearance between regulator 160 and the squeezewater valve piston decreases and that increases the pressure dropbetween the small and large diameters of the regulator. Consequently,the pressure on the large diameter of the piston decreases so that thepiston retracts. During operation, the regulator piston operates at apoint of equilibrium established by the pressures, the spring forces andthe frictional forces.

When the faucet is open, the regulator piston is operating at a point ofequilibrium and the squeeze water piston is fully retracted to allow thesqueeze water to flow. When the faucet closes, the pressure in theoutlet lines begins to increase. This increase in pressure moves theregulator piston so as eventually it pushes the squeeze water pistonclosed and thereby cuts off the flow of squeeze water. With the squeezewater valve closed, the relief valve bleeds the pressure from the tankso that permeate from the membrane can begin to fill the tank. As thepressure in the tank drops, check valve 152 prevents pressure on theregulator piston from dropping so that the squeeze water valve remainsclosed. Relief valve 134 eliminates back pressure on the reverse osmosismembrane and allows for optimal performance or rejection. Proportioningvalve 127 provides flushing of the membrane to increase life.

The described reverse osmosis system proves to be highly desirablebecause it uses a membrane to remove solids and other contaminants thatare dissolved in the water. Overall, the system measures performance andcalculates updated status each time the system is used. Together withprocessor 32, flow monitors 90 and 92 indicate to the user the status ofall of sediment filter 20, membrane filter 22 and impurity filter 28.That information is indicated both on a liquid crystal display in thecabinet and by an audio signal. The display is caused by processor 32 tosequence through the various components and display their current statuswhenever water is withdrawn from the system. Component status can bespecifically displayed using a half moon, pie or bar type percentagegraph in conjunction with the appropriate word for the component beingindicated. Status may be indicated in other ways, such as merelysignaling an "O.K.". When a component reaches a point that has beendetermined to be close to the lower functional limit of its properoperability, the audio signal is generated and this is followed by adisplay that continuously depicts a message that that component shouldbe replaced.

Processor 32 monitors the conductance of the feedwater and compares itto the conductance of the permeate water leaving the system. Moreover,the current drop caused by the ball passing between the probes in eachof the flow monitors is detected and used to determine flow rate andtotal flow each time the faucet is used. That flow rate is employed todetermine the life of the sediment filter, and the total flow isemployed to determine the life of the impurity filter. The self-cleaningprobes have the built-in temperature compensation provided by theinclusion of thermistor 674.

The flow monitor system by itself may find use in a wide variety ofdifferent apparatus. Moreover, the operational capability of processor32 together with the flow monitors may find equal applicability for usein either a sink-associated system as described or a much larger systemsuch as those for purifying water supplied to an entire residence.

As embodied, the system was designed to generate permeate at a rate ofapproximately one-fourth gallon per hour. The arrangement includingvalve unit 24 enables the system constantly to be recharging wheneverstorage tank 26 is other than completely filled. Again for this specificsink-associated application, the impurity filter has specifically beendesigned to operate satisfactorily for five-hundred gallons. Theindicator unit, as explained, signals when it should be replaced. Thetraditional beeper signal works to audibly alert the user when there isneed for replacement of any of the filters or the battery.

It will be noted that the concentrate is permitted to flow through theproportioning valve and on to the drain as well as to flow to thesqueeze side of the valve unit and travel to the storage tank where itis used as squeeze water. Permeate from the membrane filter flowsdirectly to the permeate side of the storage tank inside the bladder.During delivery of the water, the concentrate squeezes the bladder andthat forces the permeate to flow from the tank through the regulator andon through the final flow monitor. After flowing through the impurityfilter, the water finally exits through the faucet.

As indicated, the function of the regulator is to allow for operationover a wide range of incoming line pressures and as a result to provideconstant delivery of permeate to the faucet. When the faucet is opened,squeeze water from the membrane enters the storage tank at about theline pressure of the system. As squeeze water begins to collapse thebladder the permeate is in turn forced to flow to the faucet. Becausethe squeeze water flows to the tank at the same pressure, a constantdelivery of water to the faucet is obtained regardless of how full ofpermeate the storage tank may be.

While the membrane is generating permeate to fill the storage tank, theconcentrate flow is limited such that the pressure on the membrane ishigh enough for maximum removal of dissolved inorganic materials. Inaddition, the flow over the membrane is used to remove salts and isalways sufficient to prevent build up of those salts on the membrane;therefore, membrane filter life does not deteriorate. As indicated, inthe specific embodiment the flow rate of eight-to-oneconcentrate-to-permeate is maintained. The membrane is also cleansedwhen the water is delivered through the faucet.

The typical concentrate flow rates enabled by the described system areforty to three-hundred milliliters per minute, dependent upon incomingfeed water pressure. In the manner described, the proportioning valvecontrols the concentrate flow and is always open and will letconcentrate flow whenever the inlet valve is open so that water isflowing to the membrane filter. Another major function of the valve unitis to shut down the system when the permeate side of the storage tank isfull. As implemented, it is the inlet valve which is designed toaccomplish that system shut down.

While a particular embodiment of the invention has been shown anddescribed, and various alternatives and modifications have been taught,it will be obvious to those of ordinary skill in the art that changesand modifications may be made without departing from the invention inits broader aspects. Therefore, the aim in the appended claims is tocover all such changes and modifications as fall within the true spiritand scope of that which is patentable.

We claim:
 1. A flowmeter comprising:a hollow housing having an interiorwall formation that defines a circular raceway; an inlet channel leadingfrom the exterior of said housing thereinto and opening tangentiallyinto said raceway; an outlet channel leading from said raceway to theexterior of said housing; a pair of mutually-spaced direct-currentelectrically conductive probes leading from the exterior of said housinginsulatingly therethrough to exposure within said raceway; and a ballsized to move freely around said raceway when propelled by liquidflowing from said inlet channel to said outlet channel with said ballbeing of a material sufficiently abrasive to remove deposited matterfrom said electrodes and having an electrical characteristic whicheffects an electrical signal when moving thereacross.
 2. A flowmeter asdefined in claim 1 in which said liquid is water and said ball has adielectric constant higher than that of said liquid as to effect aconductivity spike when moved thereacross.
 3. A flowmeter as defined inclaim 1 in which said outlet leads outwardly from said raceway in adirection axially thereof.
 4. A flow meter defined in claim 1 whichfurther includes a temperature sensor mounted on said housing anddisposed closely adjacent to said raceway and responsive to thetemperature of said liquid flowing in said raceway to develop anelectrical signal representative of said temperature.